Giant elastocaloric effect at low temperatures in TmVO 4 and implications for cryogenic cooling

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 121; no. 25; p. e2320052121
• Main Authors: Zic, Mark P, Ikeda, Matthias S, Massat, Pierre, Hollister, Patrick M, Ye, Linda, Rosenberg, Elliott W, Straquadine, Joshua A W, Li, Yuntian, Ramshaw, B J, Fisher, Ian R
• Format: Journal Article
• Language: English
• Published: United States 18-06-2024
• Subjects: elastocaloric effect; nematicity; cryogenic cooling; quadrupolar order; quadrupole-strain susceptibility
• ISSN: 1091-6490

Adiabatic decompression of paraquadrupolar materials has significant potential as a cryogenic cooling technology. We focus on TmVO[Formula: see text], an archetypal material that undergoes a continuous phase transition to a ferroquadrupole-ordered state at 2.15 K. Above the phase transition, each Tm ion contributes an entropy of [Formula: see text] due to the degeneracy of the crystal electric field groundstate. Owing to the large magnetoelastic coupling, which is a prerequisite for a material to undergo a phase transition via the cooperative Jahn-Teller effect, this level splitting, and hence the entropy, can be readily tuned by externally induced strain. Using a dynamic technique in which the strain is rapidly oscillated, we measure the adiabatic elastocaloric response of single-crystal TmVO[Formula: see text], and thus experimentally obtain the entropy landscape as a function of strain and temperature. The measurement confirms the suitability of this class of materials for cryogenic cooling applications and provides insight into the dynamic quadrupole strain susceptibility.